The gastrointestinal (“GI”) tract is a complex micro-ecosystem in which the mucosal lining of the host coexists with billions of microorganisms that live on or are attached to the lining. Among the microorganisms that inhabit the GI tract are “probiotic” bacteria, which help to maintain the health of the GI tract of the host organism. Within the GI tract of the host, probiotic bacteria are provided with shelter and support, and copious amounts of food substrates and in return, they offer the host a variety of potential therapeutic uses including replacing intestinal bacteria destroyed by antibiotics; aiding digestion and suppressing disease-causing bacteria; preventing and treating diarrhea, including infectious diarrhea, particularly from rotavirus (a virus that commonly causes diarrhea in children); treating overgrowth of “bad” organisms in the gastrointestinal tract (a condition that tends to cause diarrhea and may occur from use of antibiotics); alleviating symptoms of irritable bowel syndrome and, possibly, inflammatory bowel disease (such as Crohn's disease and ulcerative colitis); preventing and/or reducing the recurrence of vaginal yeast infections, urinary tract infections, and cystitis (bladder inflammation); improving lactose absorption digestion in people who are lactose intolerant; and enhancing the immune response. Because probiotics have many beneficial uses, there is a need in the art for probiotic supplements.
Among the probiotics that may be included in a supplement, are Lactobacillus acidophilus, L. bulgaricus, L. casei, L. fermentum, L. paracasei, L. plantarum, L. rhamnosus, L. salivarius, Bifidobacterium bifidum, B. infantis, B. animalis subsp. lactis, B. longum, Streptococcus thermophilis, Enterococcus faecalis, and E. faecium, all of which are found in the GI and vaginal tracts of humans. The lactobacillus species are gram-positive lactic acid bacteria that absorb lactose and other monosaccharides in the intestinal tract to produce lactic acid, which has the beneficial effect of lowering the pH of the organs making the environment of the organs hostile for the growth of harmful bacterial. The bifidobacterium species are the first species of microorganisms to colonize the sterile colon of a newborn baby that is nursed by its mother. Bifidobacteria use the mechanism of crowding to digest the nutrients that otherwise harmful bacteria would use for reproduction. Probiotic supplements may have up to approximately 10 billion colony forming units per supplement.
L. acidophilus in particular has the additional beneficial effect of producing the anti-microbial substances (i.e., natural antibiotics) acidolin, acidolphilin, lactocidin, and bacteriocin, which increase the immune system's resistance against fungus, such as Candida albican, and the harmful bacterial species Escherichia coli, Staphylococcus aureus, and salmonella. 
L. bulgaricus enhances the digestibility of proteins and milk products, aids in the production of natural antibiotics, and has been used to treat gastrointestinal disorders such as enterocolitis.
L. casei has been found to have protective activity against pathogenic listeria bacteria.
L. fermentum has been found to prevent human immunodeficiency virus (“HIV”) from infecting immune cells in infants (From Reuters Health, May 25, 2004, author Karla Gale, available at http://pronutrition.org/archive/200406/msg00002.php).
L. plantarum helps produce lactolin, a natural antibiotic, and synthesizes L-lysine.
L. salivarius is a facultative bacterium (i.e., a bacterial species that survives and grows in both anaerobic and aerobic environments) that is most abundant in the mouth and gums. L. salivarius has several advantages as a probiotic: it has the ability to break down undigested protein and disengage the toxins produced by protein putrefactions; it is useful to prevent and fight Helicobacter pylori, which is known to be a cause of ulcers); and because its population doubles every 20 minutes, smaller amounts of the probiotic may be administered to a patient thus lending an economic advantage to the use of the probiotic.
L. rhamnosus has excellent stability over a wide range of temperatures and pH levels; it relieves hypersensitivity reactions and intestinal inflammation in individuals with eczema and food allergies.
B. animalis is a probiotic bacterium that plays a role in intestinal mucosal defense. B. animalis has two subspecies: B. animalis subsp. animalis and B. animalis subsp. lactis, both of which prior to 2004 were referred to as B. animalis and B. animalis subsp. lactis. Masco et al., INT'L J SYST EVOL BIOL 54:1137-1143 (2004). Because B. animalis subsp. animalis only grows in anaerobic environments and is incapable of growth in milk cultures, it is not useful as a probiotic. By contrast, B. animalis subsp. lactis, which is a lactic acid bacterium characterized by its high oxygen resistance and production of considerable amounts of formate, grows well in milk cultures and thus, is a useful probiotic. B. animalis subsp. lactis is added to infant formulas to ensure that newborn babies not being nursed have sufficient colonization of bifidobacteria and is the only bifidobacterium species that is found in yogurt cultures.
B. bifidum inhibits the growth of the harmful bacterial species salmonella, listeria, shigella, E. coli, and Clostridium perfringens by consuming their nutrients, such as for example, ferrous ions, which many harmful bacterial species require for growth. B. bifidum also synthesizes some vitamins and aids in the absorption of minerals such as calcium, magnesium, and zinc.
B. infantis is the first probiotic to colonize the sterile digestive tract of an infant that is nursed by its mother. For infants that are formula fed, this probiotic may be administered in supplemental form in order to ensure that the newborn has the proper intestinal flora.
B. longum biovar longum (referred to as B. longum) has been found to be able to eliminate nitrates from the intestinal tract.
S. thermophilis generates lactase activity, facilitating the digestion of lactose in milk.
E. faecalis and E. faecium are both lactic acid bacteria that have inhibitory effects against enteropathogens such as E. coli, salmonellae, shigellae and clostridia.
U.S. Pat. No. 4,518,696 to Gehrman et al. teaches the use of sunflower oil as a liquid suspending medium for preparing dry viable lactobacillus cells that are stable at room temperature.
U.S. Pat. No. 5,466,463 to Ford teaches a vaginal suppository containing an antimicrobial agent and a viable colony of microencapsulated lactobacilli bacteria; the bacteria are microencapsulated to protect them from the action of the antimicrobial agent.
U.S. Pat. Nos. 5,614,209; 5,633,012; 5,635,202; and 5,733,568 all to Ford teach microencapsulated lactobacilli bacteria for oral and topical administration to mammals that have 103 viable microencapsulated lactobacilli in each unit dose.
U.S. Pat. No. 6,706,287 to Ranganathan et al. teaches microencapsulated and/or enteric-coated probiotics, such as lactobacillus and bifidium bacteria species, that are capable of metabolizing urea and ammonia to amino acids.
A disadvantage of many of the probiotic formulations on the market is the poor shelf life of the formulations; accordingly, there is a need in the art for improved shelf life of probiotic formulations having live colonies of probiotic bacteria, such as for example, lactobacillus and bifidobacterium. 